Patent GB-753740-A (GB)
Title: Improvements in and relating to the reductive alkylation of organic compounds
Inventor: ROSENWALD ROBERT HENRY
Filed: 1954-02-26
Abstract: Organic compounds containing amino and/or nitro groups are subjected to reductive alkylation with ketones or aldehydes and hydrogen, in the presence of a platinum containing catalyst having a platinum content of not more than 2 per cent by weight, and which prior to use in the reductive alkylation has been pretreated with a reducing agent at a temperature above 95 DEG  C. (see Group III).  Specified organic compounds are mono-, di- and tri-nitrobenzenes, aniline, di- and tri-aminobenzenes, aminonitrobenzenes, diaminonitrobenzenes, aminodinitrobenzenes, similarly substituted naphthalene and anthracene compounds, and nitro- or amino- or nitroamino-phenols; C1-8 monoalkylamines, ethylene-, propylene-, butylene-, amylene-, trimethylene-, tetramethylene-, pentamethylene- and hexamethylene-diamines, diethylene- and dipropylene-triamines, C2-8 monoalkanolamines, and diethanolamine; mono- and polynitro- or amino-cyclohexanes, cyclopentanes, pyridines and thiophenes. Specified ketones are methyl C1-8 alkyl ketones, ethyl C2-7 alkyl ketones, propyl C3-6 alkyl ketones, butyl C3-6 alkyl ketones, cyclohexanone, acetophenone, benzophenone, C2-5 alkyl phenyl ketones and C1-4 alkyl cyclohexyl ketones.  Aldehydes specified are formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and valeraldehyde.  Mixtures of ketones or aldehydes may be used. Preferably p-nitroaniline, p-phenylene diamine, p-nitrophenol or p-aminophenol are reacted with dialkyl ketones wherein one alkyl group has up to 4 carbon atoms and the other up to 8, to give an N:N1-di - secondary - alkyl - p - phenylenediamine or an N-secondary alkyl-p-aminophenol, a slight excess of ketone and hydrogen over the stoichiometrical equivalent being employed.  The reductive alkylation which may be a batchwise or continuous process is effected at a pressure of from about 7 to about 200 atmospheres and at temperature between 10 DEG  and 260 DEG  C.  In examples: (1-7) p-nitroaniline is reacted with methyl ethyl ketone to give N:N1 - di - secondary - butyl - p - phenylenediamine in the presence of various catalysts as defined above; (8) p-nitrophenol is reacted with ethyl butyl ketone to give N-(3-heptyl)-p-aminophenol.ALSO:Catalysts used in the alkylation of organic amino and/or nitro compounds with ktones or aldehydes and hydrogen (see Group IV(b)) contain not more than 2 per cent. by weight of platinum and are pretreated with a reducing agent at a temperature above 95 DEG C. Any suitable carrier may be used, a difficulty reducible metal oxide being preferred.  Specified carriers are natural or prepared alumina, silica, asbestos, charcoal, zinc oxide, magnesium oxide, molybdenum oxide, thorium oxide, zirconium oxide, silica-alumina, silica-zirconia, silica-magnesia, silica-thoria, silica-alumina-zirconia, silica-alumina-magnesia, silica-alumina-thoria, silica-zirconia-thoria and zirconia-magnesia-thoria.  The catalysts may also contain between 0.1 and 8.0 per cent combined halogen, i.e. fluorine and/or chlorine. The platinum is composited with the support by using an aqueous solution of a soluble platinum compound such as chloroplatinic acid, ammonium platinum chloride, trimethylbenzyl ammonium platinum chloride, tetraamino-platino chloride and ammonium platino-nitrate. This is mixed with the carrier, the mixture evaporated to dryers, ground and when desired, formed into particles or pellets. Alternatively when the carrier is prepared synthetically (e.g. alumina) it may be formed into spheres, composited with the platinum and subsequently dried and calcined.  The pretreatment of the catalyst with the reducing agent is preferably carried out at above 315 DEG C. but not above 650 DEG C., for from 1 to 12 hours and at a pressure of up to 150 atmospheres.  Hydrogen may be used alone or in admixture with hydrocarbons such as paraffins and isoparaffins ranging from propane to dodecane and higher boiling paraffins, olefines, naphthenes, aromatics gasoline and naphthas.  Alternatively the hydrocarbon may be a substance such as tetra- or deca-hydronaphthalene which acts as a hydrogen donor.  The pretreatment may be effected by a hydrocarbon alone.  In examples; (1) activated alumina pills were treated with aqueous chloroplatinic acid, dried, calcined at 500 DEG C. for 3 hours in air to give a catalyst containing 0.3 per cent platinum which was then pretreated in the presence of hydrogen and straight-run naphtha at 450 DEG C. and 34 atmospheres pressure for 20 hours; (2) prepared alumina was treated with hydrofluoric acid to give a fluorine content of 0.3 per cent, made into pills and then treated similarly to (1); (3) catalysts containing various percentages of platinum were prepared; (5) catalysts using as supports charcoal, asbestos and silica were prepared; (7) as in (2) but the catalyst was pretreated with a heptane fraction at about 316 DEG C. and at atmospheric pressure for 4 1/2 hours.